1. Field of the Invention
This invention relates to a reverse trap printed, heat shrinkable, oriented thermoplastic film. The invention particularly relates to a reverse trap printed, heat shrinkable, oriented thermoplastic film roll stock, heat shrinkable containers make therefrom and methods for producing said film roll stock and said containers.
2. Description of the Related Art
Transparent or translucent plastic containers are often used in the packaging of fresh meats and poultry. This type of transparent or translucent plastic container having a "bone patch" is also commonly used for bone-in primal cuts of meat and for large carcass poultry such as turkey. In addition to protecting the packaged meat product the plastic container commonly has printed matter visible on the outside of the package. Commonly, the printing is done on the outside surface of the plastic container. In order to offer some protection to the printed matter from abrasive damage a coat of varnish or other protective layer may be applied over the printing. Another known method is to print on the container outer surface before applying the patch and then providing a layer of adhesive over the printing and adhering the patch to this layer of adhesive. The adhesive may be applied directly over the printing or, preferably, is applied to one surface of the patch material before attachment to the food container over the printing. An improved method of protecting the printing is the use of reverse printing on a second layer of film which is then bonded to the first, product containing film layer. An example of this type of reverse printed container is disclosed in U.S. Pat. No. 5,190,609 issued Mar. 2, 1995 to Lin et al. This reference teaches the use of a heat shrinkable label formed of polyolefin such as polypropylene having a layer of adhesive, a layer of printing and a second layer of adhesive, with or without a second layer of polyolefin film to form a label for adhesive attachment to the outside of a container. This teaching requires an adhesive layer between the printing and the layer of film covering the printing. This reference also discloses the use of a varnish over the printing when the printing is applied to the outer surface of the polyolefin film in a traditional, non-reverse, printing method. A trap printed package for snack foods comprising an outer layer of polypropylene having reverse printing thereon is coated on the printed side with a primer coating which provides bonding adhesion for the PVDC barrier layer attached thereto is disclosed in U.S. Pat. No. 4,442,158 issued Apr. 10, 1984 to Distler. An inner surface layer of ionomer resin to prevent Cl migration to the contained food product is also required.